The space age is barely two decades old, but the steps taken during that time have created unparalleled opportunities for the exploration and use of outer space. The Space Shuttle has been a step which has greatly facilitated this opportunity.
The Space Shuttle is a versatile vehicle having the essential characteristics of a spacecraft; yet is, in some respects, similar to an aircraft. The Shuttle ascends into outer space with the assistance of rockets just as do conventional spacecraft and descends from outer space, in a manner reminiscent of the landing of an aircraft, by gliding through the atmosphere and landing on a runway. The development of the Shuttle is a significant achievement because it marks the advent of a rudimentary space transportation system. This system allows man and cargo to "shuttle" routinely to and from outer space, thereby making it possible to service, repair and resupply spacecraft, to build larger structures, such as industries, and eventually to construct settlements in outer space.
In a technical sense, the Space Shuttle is made up of an orbiter, an external tank containing the ascent propellant used by the orbiter's main engines (SSME's) and two solid rocket boosters. The orbiter and the solid rocket boosters are reusable, while the external tank is expendable on each launch. At launch, the two solid rockets and the orbiter's three liquid rocket engines ignite and burn simultaneously. The orbiter, with its crew and payload, remains in orbit to carry out a mission, normally for about seven days, When the mission is completed, the orbiter returns to Earth and lands in a fashion similar to an airplane.
While the Space Shuttle marks a major step forward in the development of outer space, a number of problems prevent the Space Shuttle from being the most effective, economical, and efficient method of conveying materials to outer space. In particular, the National Space Transportation System (NSTS) has been at a virtual standstill since the Shuttle Challenger accident of Jan. 28, 1986. Since the Shuttle accident, there has been a goal of finding a cost-effective path to restore the launch capability which was earlier planned by NASA to be provided by twenty-four (24) flights per year of the four (4) Space Shuttle orbiter vehicles. At the present time, more cautious and more realistic estimates by NASA are that the three remaining Shuttle orbiters, when restored to flight status in 1988, can provide about eight (8) launches per year. When OV-105, the replacement Shuttle orbiter, is delivered in 1991 or 1992, the maximum launch capability is now expected to be about fourteen (14) flights per year, less than 60% of 1985 expectations.
The United States Air Force has previously initiated development of a new version of the Titan expendable launch vehicle, the Titan 4, to conduct one or two flights per year for five (5) years for essential national security missions as a back-up to the Shuttle, previously designated as the nation's only large space launch vehicle. Since the accident, another thirteen (13) Titan 4's have been placed on order to fulfill some of the military needs which were assigned to the Shuttle.
The premier new program of NASA is the low Earth-orbit Space Station, planned to be placed in space in the early 1990's and continuously manned thereafter. Current plans are that twelve (12) to over thirty (30) NSTS flights will be required to build the Space Station in orbit from a number of Shuttle-sized payloads and that a minimum of four (4) flights per year thereafter will be required to provide for Space Station crew rotation and logistics resupply.
Many science and commercial payloads will have to seek other means of attaining orbit, as the two large U.S. systems--Titan 4 and Shuttle--are saturated for the indefinite future. Other launch vehicles, notably the French "Ariane" may fill the breach for the small and medium space payloads, but the prospective availability and pricing structure of the Shuttle has greatly impacted many users' plans for satellite scale -- dimensions of 15 feet diameter and 60 feet length and mass up to 65,000 pounds have, over the past ten years, become a de facto standard.
It is necessary to develop a means of fulfilling the initial Shuttle promise--adequate capacity for all users with the capability of placing payloads into space of up to 65,000 pounds and 15 feet by 60 feet in size. In addition, it is necessary to find a means of placing into orbit the brand new "Centaur" upper stage vehicle for planetary exploration. Since one aftermath of the Challenger accident was increased awareness of the hazardous nature of a large, cryogenic propellant vehicle, all plans to fly the "Centaur" vehicle in the manned Shuttle vehicle have been cancelled.
It is an object of the present invention to provide a space launch vehicle that is capable of allowing the recovery of most of the expensive components of launches.
It is another object of the present invention to provide a space launch vehicle that does not require the use of solid rocket boosters to achieve orbit.
It is another object of the present invention to provide a space launch vehicle that utilizes SSME's for liftoff and, thereby, adds to the experience base of the SSME's so as to enhance the maturation of the Space Shuttle.
It is another object of the present invention to provide a launching method that allows cargo to be transported into outer space with a minimum of expense related to the development of new technology.
It is another object of the present invention to provide a space launch vehicle and method of launching that can enable the use of high energy cryogenic propellant upper stages for planetary exploration.
It is still a further object of the present invention to provide a space launch vehicle whose upper stage remains in space for future constructive use.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specifications and appended claims.